WO2018174095A1 - レールおよびその製造方法 - Google Patents
レールおよびその製造方法 Download PDFInfo
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- WO2018174095A1 WO2018174095A1 PCT/JP2018/011193 JP2018011193W WO2018174095A1 WO 2018174095 A1 WO2018174095 A1 WO 2018174095A1 JP 2018011193 W JP2018011193 W JP 2018011193W WO 2018174095 A1 WO2018174095 A1 WO 2018174095A1
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- proof stress
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- 238000004519 manufacturing process Methods 0.000 title claims description 12
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 48
- 239000010959 steel Substances 0.000 claims abstract description 48
- 238000007689 inspection Methods 0.000 claims abstract description 28
- 239000000203 mixture Substances 0.000 claims abstract description 19
- 238000005259 measurement Methods 0.000 claims abstract description 14
- 239000012535 impurity Substances 0.000 claims abstract description 8
- 239000000463 material Substances 0.000 claims description 28
- 238000012360 testing method Methods 0.000 claims description 13
- 229910052717 sulfur Inorganic materials 0.000 abstract description 2
- 230000035882 stress Effects 0.000 description 53
- 238000012937 correction Methods 0.000 description 26
- 238000000034 method Methods 0.000 description 20
- 230000032683 aging Effects 0.000 description 19
- 229910001562 pearlite Inorganic materials 0.000 description 16
- 238000009864 tensile test Methods 0.000 description 16
- 230000000694 effects Effects 0.000 description 12
- 238000005096 rolling process Methods 0.000 description 9
- 238000005728 strengthening Methods 0.000 description 9
- 238000005098 hot rolling Methods 0.000 description 8
- 239000002244 precipitate Substances 0.000 description 8
- 230000007423 decrease Effects 0.000 description 7
- 229910000734 martensite Inorganic materials 0.000 description 7
- 238000001816 cooling Methods 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 6
- 238000005452 bending Methods 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 238000001556 precipitation Methods 0.000 description 5
- 238000005275 alloying Methods 0.000 description 4
- 229910001567 cementite Inorganic materials 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 description 4
- 239000006104 solid solution Substances 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 230000001747 exhibiting effect Effects 0.000 description 2
- 238000005065 mining Methods 0.000 description 2
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 238000009749 continuous casting Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 238000009661 fatigue test Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 150000001247 metal acetylides Chemical class 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Images
Classifications
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/002—Heat treatment of ferrous alloys containing Cr
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D7/00—Modifying the physical properties of iron or steel by deformation
- C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
- C21D7/10—Modifying the physical properties of iron or steel by deformation by cold working of the whole cross-section, e.g. of concrete reinforcing bars
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0025—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings of elongated objects, e.g. pipes, masts, towers or railways
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
- G01M5/0041—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining deflection or stress
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/009—Pearlite
Definitions
- the present invention relates to a rail, in particular, a high-strength pearlite rail and a manufacturing method thereof.
- this type of rail is used under severe high axial load conditions, such as mining railways with heavy freight cars and many sharp curves, so fatigue resistance is suitable for extending the life of the rails. It provides a way to provide a high-strength pearlite rail with excellent damage.
- Patent Document 1 proposes a rail excellent in wear resistance, fatigue damage resistance, and delayed fracture resistance, in which the ratio between the Mn amount and the Cr amount and the ratio between the V amount and the N amount are specified.
- Patent Document 2 proposes a method for manufacturing a pearlite rail excellent in wear resistance and ductility, in which the amounts of C and Cu are specified and post-heat treatment is performed at a heating temperature of 450 ° C. to 550 ° C. for 0.5 h to 24 h. ing.
- Patent Document 3 proposes a pearlite rail having excellent wear resistance and surface damage resistance, in which the C amount and the structure are specified, and the 0.2% proof stress is 600 to 1200 MPa.
- the pearlite steel rail which specified C, Si, Mn, P, S, Cr amount and the total of C, Si, Mn, and Cr content, and 0.2% proof stress is more than 500 MPa and less than 800 MPa. Has been proposed.
- Japanese Patent No. 5292875 Japanese Patent No. 5493950 JP 2000-219939 A Japanese Patent No. 5453624
- a rail obtained through hot rolling and accelerated cooling is subjected to a straightening process in order to eliminate the bending.
- the 0.2% proof stress is considerably lowered due to the Bauschinger effect. That is, in order to impart straightness to the rail, it is necessary to perform correction with a load of 30 to 70 tf, for example.
- the 0.2% proof stress after the correction process is significantly reduced as compared with that before the correction process. Therefore, it is necessary to add an alloying element and sufficiently increase the 0.2% proof stress before the rail straightening treatment.
- the addition of a large amount of the alloying element leads to the generation of an abnormal structure other than the pearlite structure. Therefore, it is difficult to add alloying elements beyond the current level. Therefore, it is necessary to suppress the 0.2% proof stress, which decreases due to the Bauschinger effect, by a method other than the addition of alloy elements.
- the pearlite steel rail described in Patent Document 4 has a low 0.2% proof stress of less than 800 MPa, and it is difficult to ensure fatigue damage resistance.
- the present invention has been made in view of the above circumstances, and proposes a method for realizing a high 0.2% proof stress in a rail after product shipment, which is effective in improving the fatigue resistance of the rail. Objective.
- the summary structure is as follows. 1. At least a rail provided with a steel material inspection certificate in which a measurement result of 0.2% proof stress of the rail head is described, % By mass C: 0.70 to 0.85%, Si: 0.1 to 1.5%, Mn: 0.4 to 1.5%, P: 0.035% or less, S: 0.010% or less and Cr: 0.05-1.50% And the balance has a component composition of Fe and inevitable impurities, A rail whose 0.2% proof stress is 40 MPa or more after at least 90 days from the date of creation of the steel test certificate, with respect to the 0.2% proof stress described in the steel test certificate.
- the component composition is further mass%, V: 0.30% or less, Cu: 1.0% or less, Ni: 1.0% or less, Nb: 0.05% or less, Mo: 0.5% or less, Al: 0.07% or less, W: 1.0% or less,
- a steel material having the composition of Fe and the inevitable impurities in the balance is hot-rolled to produce a rail, and the rail is corrected with a load of 100 tf or more.
- a rail manufacturing method for creating a steel inspection certificate including a measurement result of 0.2% proof stress of a head.
- the component composition is further mass%, V: 0.30% or less, Cu: 1.0% or less, Ni: 1.0% or less, Nb: 0.05% or less, Mo: 0.5% or less, Al: 0.07% or less, W: 1.0% or less, 4.
- the rail manufacturing method according to 3 above which contains one or more selected from the group consisting of B: 0.005% or less and Ti: 0.05% or less.
- C 0.70 to 0.85% C is an element that forms cementite in a pearlite structure and has an effect of improving 0.2% proof stress by aging at room temperature. Therefore, the addition of C is indispensable to ensure the 0.2% proof stress of the rail, and the 0.2% proof stress is improved as the C content increases. That is, when the C content is less than 0.70%, it is difficult to obtain an excellent 0.2% yield strength after the normal temperature aging. On the other hand, if the C content exceeds 0.85%, pro-eutectoid cementite is generated at the prior austenite grain boundaries, and the fatigue damage resistance of the rail is reduced. Therefore, the C content is set to 0.70 to 0.85%. Preferably, it is 0.75 to 0.85%.
- Si 0.1 to 1.5%
- Si is an element having an effect as a deoxidizer. Moreover, Si has the effect of improving the 0.2% proof stress of the rail by solid solution strengthening to ferrite in pearlite. Therefore, the Si content needs to be 0.1% or more. On the other hand, if the Si content exceeds 1.5%, a large amount of oxide inclusions are generated due to the high bonding strength with Si, and fatigue resistance is reduced. Therefore, the Si content is 0.1 to 1.5%. Preferably, it is 0.15 to 1.5%.
- Mn 0.4 to 1.5%
- Mn is an element that contributes to increasing the strength of the rail by reducing the lamellar spacing by lowering the transformation temperature of the steel.
- the Mn content is less than 0.4%, a sufficient effect cannot be obtained.
- the Mn content exceeds 1.5%, a martensite structure is likely to be generated due to microsegregation of steel, and as a result, fatigue damage resistance is reduced. Therefore, the Mn content is 0.4 to 1.5%. Preferably, it is 0.4 to 1.4%.
- the P content exceeds 0.035%, the ductility of the rail decreases. Therefore, the P content is 0.035% or less.
- the lower limit of the P content is not particularly limited, and may be 0%, but industrially exceeds 0%.
- the P content is preferably set to 0.001% or more from the viewpoint of economy. More preferably, it is 0.025% or less.
- S 0.010% or less S is present in steel mainly in the form of A-based (sulfide-based) inclusions.
- A-based (sulfide-based) inclusions When the S content exceeds 0.010%, the amount of the inclusions is remarkably increased and coarse inclusions are generated, so that the fatigue damage resistance is lowered.
- S content 0.0005% or more In order to make S content less than 0.0005%, since the refining cost will be increased, it is preferable to make S content 0.0005% or more from a viewpoint of economical efficiency. More preferably, it is 0.009% or less.
- Cr 0.05 to 1.50% Cr is an element having an effect of improving the 0.2% yield strength by solid solution strengthening to cementite in pearlite. In order to obtain this effect, the Cr content needs to be 0.05% or more. On the other hand, if the Cr content exceeds 1.50%, a martensitic structure is generated by strengthening the solid solution of Cr, so that the fatigue damage resistance is lowered. Therefore, the Cr content is 0.05 to 1.50%. Preferably, it is 0.10 to 1.50%.
- the steel material of the rail of the present invention contains the above components, and the balance contains Fe and inevitable impurities.
- the balance may be made of Fe and unavoidable impurities, but can further contain the following elements within a range that does not substantially affect the operational effects of the present invention.
- V 0.30% or less
- Cu 1.0% or less
- Ni 1.0% or less
- Nb 0.05% or less
- Mo 0.5% or less
- Al 0.07% or less
- W 1.0% or less
- One type or two or more types selected from the group consisting of B: 0.005% or less and Ti: 0.05% or less can be further contained as necessary.
- V 0.30% or less
- V is an element that precipitates as carbonitride during and after rolling and has an effect of improving 0.2% proof stress by precipitation strengthening. For that purpose, it is preferable to add at 0.001% or more. On the other hand, if the V content exceeds 0.30%, a large amount of coarse carbonitride precipitates, resulting in a decrease in fatigue damage resistance. Therefore, when adding V, it is preferable to make V content 0.30% or less.
- Cu 1.0% or less
- Cu like Cr, is an element having an effect of improving 0.2% proof stress by solid solution strengthening. For that purpose, it is preferable to add at 0.001% or more. On the other hand, if the Cu content exceeds 1.0%, Cu cracking occurs. Therefore, when adding Cu, it is preferable to make Cu content 1.0% or less.
- Ni 1.0% or less Ni has an effect of improving 0.2% proof stress without deteriorating ductility. For that purpose, it is preferable to add at 0.001% or more. Moreover, since Cu cracking can be suppressed by adding Ni in combination with Cu, it is desirable to add Ni when Cu is added. On the other hand, if the Ni content exceeds 1.0%, the hardenability is increased and martensite is generated, resulting in a decrease in fatigue damage resistance. Therefore, when adding Ni, it is preferable to make Ni content into 1.0% or less.
- Nb 0.05% or less Nb precipitates as carbonitride during and after rolling, and improves the 0.2% yield strength of the pearlite rail. For that purpose, it is preferable to add at 0.001% or more. On the other hand, if the Nb content exceeds 0.05%, a large amount of coarse carbonitride precipitates, resulting in a decrease in ductility. Therefore, when Nb is added, the Nb content is preferably 0.05% or less.
- Mo 0.5% or less Mo precipitates as carbide during and after rolling, and improves 0.2% proof stress by precipitation strengthening. For that purpose, it is preferable to add at 0.001% or more. On the other hand, when the Mo content exceeds 0.5%, martensite is generated, and as a result, fatigue damage resistance is lowered. Therefore, when adding Mo, it is preferable to make Mo content into 0.5% or less.
- Al 0.07% or less
- Al is an element added as a deoxidizer. For that purpose, it is preferable to add at 0.001% or more. On the other hand, if the Al content exceeds 0.07%, a large amount of oxide inclusions are generated due to the binding force of Al with high oxygen, and as a result, fatigue damage resistance is reduced. Therefore, the Al content is preferably 0.07% or less.
- W 1.0% or less W precipitates as carbide during and after rolling, and improves 0.2% proof stress by precipitation strengthening. For that purpose, it is preferable to add at 0.001% or more. On the other hand, when the W content exceeds 1.0%, martensite is generated, and as a result, the fatigue damage resistance is lowered. Therefore, when adding W, it is preferable to make W content into 1.0% or less.
- B 0.005% or less B precipitates as a nitride during and after rolling and improves 0.2% proof stress by precipitation strengthening. Therefore, it is preferable to add at 0.0001% or more. However, when the B content exceeds 0.005%, martensite is generated, and as a result, fatigue damage resistance is lowered. Therefore, when adding B, it is preferable to make B content 0.005% or less.
- Ti 0.05% or less Ti precipitates as carbide, nitride, or carbonitride during and after rolling and improves 0.2% proof stress by precipitation strengthening. For that purpose, it is preferable to add at 0.001% or more. On the other hand, when the Ti content exceeds 0.05%, coarse carbides, nitrides or carbonitrides are generated, and as a result, fatigue damage resistance is lowered. Therefore, when adding Ti, it is preferable to make Ti content 0.05% or less.
- the straightening treatment and aging treatment according to the above conditions are effective, the straightening treatment under the optimum load and the normal temperature aging in the optimum period.
- the 0.2% yield strength after at least 90 days can be improved.
- the 0.2% yield strength improvement margin is less than 40 MPa, the 0.2% yield strength improvement margin is small, so plastic flow tends to occur on the rail surface, and a fatigue layer tends to accumulate on the rail surface. The fatigue damage improvement margin is reduced. Therefore, the 0.2% yield strength improvement is 40 MPa or more.
- the “0.2% proof strength improvement allowance” means the date of creation of the “steel inspection certificate” after rail manufacture, that is, the 0.2% proof strength of the rail at the time of shipment (hereinafter referred to as the pre-aging rail), Difference from 0.2% proof stress obtained by performing a tensile test on a specimen taken from a rail that has passed at least 90 days from the date of creation (hereinafter referred to as an aging rail) (0.2% proof strength of aging rail minus pre-aging rail 0.2% proof stress).
- the improvement margin of 0.2% proof stress after at least 90 days is defined as the strain aging that C is fixed to the strain introduced into the rail when the rail is straightened and the 0.2% proof stress is increased. This is for the purpose of evaluating 0.2% yield strength after sufficient expression.
- the steel material inspection certificate describes the result of a test such as mechanical properties of the rail that has undergone the final manufacturing process of the rail. When the rail is shipped, a steel material inspection certificate for the rail is attached and shipped to the customer. The steel material inspection certificate is attached to the rail of the present invention, and the steel material inspection certificate describes at least the measurement result of 0.2% proof stress of the head of the rail.
- the measurement result of 0.2% yield strength described here is an actual measurement value obtained by performing a tensile test on a sample collected from the head of the rail.
- 0.2% proof stress 40 MPa or more with respect to the 0.2% proof stress described in the steel material inspection certificate.
- it takes 90 days or more from rail shipment to rail installation it has improved fatigue damage resistance compared to the fatigue damage resistance expected from the 0.2% proof stress described in the steel inspection certificate. It will be a thing. Even if it takes less than 90 days from the date of creation of the steel inspection certificate to the laying of the rail, the rail life is usually much longer than 90 days.
- the 0.2% proof strength improvement fee may be measured at least after 90 days from the date of creation of the steel material inspection certificate, and should not be measured after 90 days. That is, the measurement of the improvement margin of 0.2% proof stress may be 90 days after the date of creation of the steel material inspection certificate or after one year or more. This improvement of 0.2% proof stress of 40 MPa or more may be judged as a safety allowance for the predicted life of the rail, or an additional 40 MPa is added to the 0.2% proof stress described in the steel inspection certificate. The life of the rail can also be predicted based on the obtained value.
- the rail according to the present invention can be manufactured by preparing a rail by hot rolling and then cooling according to a conventional method, and then performing a correction treatment with a load of 100 tf or more.
- the production of the rail by hot rolling can be performed, for example, by the following procedure. First, steel is melted in a converter or an electric furnace, and the composition of the steel is adjusted to the above range through secondary refining such as degassing as necessary. Next, continuous casting is performed to obtain a steel material such as bloom. Next, the steel material is heated to 1200 to 1350 ° C. in a heating furnace and then hot-rolled to obtain a rail.
- the hot rolling is preferably performed at a rolling end temperature of 850 to 1000 ° C., and the rail after hot rolling is preferably cooled at a cooling rate of 1 to 10 ° C./s.
- FIG. 3 is a conceptual diagram showing the rail curving correction method.
- the rail curving is corrected by passing the rail R through the correcting rollers A to G arranged in a staggered manner along the rail conveying line. .
- the upper surface positions of the correction rollers A, B, and C arranged on the lower side of the conveyance line are arranged above the lower surface positions of the correction rollers D, E, F, and G arranged on the upper side of the conveyance line.
- the rail is repeatedly bent and bent back.
- at least one of the correction loads applied to the correction rollers A to G is set to 100 tf or more.
- the correction load is preferably 105 tf or more and 170 tf or less.
- the strain accumulated in the rail by the straightening process varies depending on the straightening load and the cross-sectional area (rail size) of the rail to be straightened.
- the size of the rail used under the high axial load condition which is the main object of the present invention is 115 lbs, 136 lbs and 141 lbs in the North American AREMA standard having a relatively large cross section, and 50 kgN and 60 kgN in the JIS standard.
- the above-mentioned correction load is set to 100 tf or more, a 0.2% yield improvement margin relative to the 0.2% yield measured within 480 hours after the above correction can be sufficiently obtained. Can be stored on the rail.
- a steel material inspection certificate including at least the 0.2% proof stress measurement result of the rail head will be created within 480 hours. If the rail material inspection including 0.2% proof stress is performed after a long period of time that causes strain aging after the rail bend correction, the 0.2% proof stress will be higher than that immediately after the correction, so it is high 0 Can be shipped as a rail with 2% yield strength. However, it is impossible to store the rails in the factory for a long time after the straightening process because of the limitation of the storage area. Therefore, a steel material inspection certificate describing at least the 0.2% proof stress measurement result of the rail head is prepared immediately after the above-mentioned bending correction, specifically within 480 hours.
- the rail produced from the steel material having the above-described component composition is subjected to the above straightening treatment and then subjected to room temperature aging for at least 90 days, so that at least 90 days have passed since the date of creation of the steel material inspection certificate.
- the margin for improving the% yield strength is 40 MPa or more.
- a steel material (bloom) having the component composition shown in Table 1 was hot-rolled to produce a rail having the size shown in Table 2.
- the heating temperature before hot rolling was 1250 ° C.
- the rolling exit temperature was 900 ° C.
- the rail after hot rolling was cooled to 400 ° C. at an average cooling rate of 3 ° C./s.
- the rail after completion of cooling was subjected to straightening treatment according to the conditions shown in Table 2.
- Each of the obtained rails was subjected to a tensile test to measure 0.2% proof stress, tensile strength and elongation.
- a fatigue damage resistance test was performed to measure the fatigue damage resistance of each rail. Table 2 also shows the results of these tests.
- the measurement method was as follows. The tensile test is performed between the straightening process and the preparation of the steel material inspection certificate. Except for 1, it was also carried out after the room temperature aging treatment.
- the tensile test was performed within 480 hours after the test piece was collected from the rail head immediately after the correction process (within 480 hours). Except for 1, the test was carried out 90 days after the steel material inspection certificate was created. Samples are also taken from the head of the rail that has been subjected to room temperature aging treatment as shown in Table 2, and after the time (days) from the steel material inspection certificate creation to the tensile test shown in Table 2 has elapsed. A tensile test was also conducted. And the improvement margin (MPa) of the 0.2% proof stress after normal temperature aging treatment was calculated
- MPa improvement margin
- Fatigue damage resistance was evaluated by simulating actual rail-wheel contact conditions using a Nishihara-type wear tester. That is, a cylindrical test piece having a diameter of 30 mm (outer diameter 30 mm, inner diameter 16 mm) having a curved surface with a curvature radius of 15 mm is taken from the rail head portion shown in FIG. 2A of the rail after normal temperature aging treatment. did. As shown in FIG. 2B, the cylindrical test piece was subjected to contact pressure: 2.2 GPa, slip rate: ⁇ 20%, and oil lubrication conditions in a test machine, and the point at which peeling occurred on the test piece contact surface. The fatigue life was assumed. Fatigue damage resistance when a pearlite steel rail with a C content of 0.81% is used as a standard for comparing the magnitude of fatigue damage life and the fatigue damage time is 10% or longer than the rail (A1). Was determined to have improved.
- the wheel material shown in FIG. 2 is 0.76% C-0.35% Si-0.85% Mn-0.017% P-0.008% S-0.25% Cr in mass%.
- the round bar of diameter 33mm which has the component composition of remainder Fe and an unavoidable impurity is heated to 900 degreeC, hold
- the wheel material had a hardness of HV280.
- Rail No. 1 is a currently used pearlite rail having a C content of 0.81%.
- the rails of the inventive examples manufactured according to the present invention are all the comparative example No. In addition to exhibiting 0.2% yield strength superior to that of rail No. 1 by 40 MPa or more, it was provided with a 10% or more fatigue damage resistance improvement allowance.
- the rail of the comparative example which does not satisfy the conditions of the present invention was inferior in at least one of 0.2% yield strength, elongation and fatigue damage resistance.
- a rail was prepared in the same manner as in Example 1 except that steel having the component composition shown in Table 3 was used, and a tensile test and fatigue damage resistance measurement were performed in the same manner as in Example 1.
- Table 4 shows the correction treatment and aging treatment conditions and the measurement results.
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Abstract
Description
そこで、合金元素を添加し、レールの矯正処理前の0.2%耐力を十分に上昇させておく必要が生じるが、合金元素の多量添加は、却ってパーライト組織以外の異常組織の生成をまねくため、現状以上の合金元素の添加は困難である。従って、バウシンガー効果により低下する0.2%耐力を合金元素の添加以外の手法で抑制する必要がある。
特許文献2では、CおよびCu量を規定し、450℃~550℃の加熱温度で0.5h~24hの後熱処理を施すことが提案されているが、加熱温度が高く、却って転位の回復により0.2%耐力の低下を招くため、矯正処理後の0.2%耐力はより低いものとなる。
特許文献3に記載の技術では、C量を0.85%超えとし、セメンタイト量を増加させることで高い0.2%耐力を確保する一方で、伸びが低下してレールに亀裂が入りやすくなるため、耐疲労損傷性を確保することができない。
特許文献4に記載のパーライト鋼レールは、0.2%耐力が800MPa未満と低く、耐疲労損傷性の確保が困難であるのが実状である。
1.少なくともレール頭部の0.2%耐力の測定結果が記載された鋼材検査証明書を備えるレールであって、
質量%で、
C :0.70~0.85%、
Si:0.1~1.5%、
Mn:0.4~1.5%、
P :0.035%以下、
S :0.010%以下および
Cr:0.05~1.50%
を含有し、残部がFeおよび不可避的不純物の成分組成を有し、
前記鋼材検査証明書に記載された0.2%耐力に対して、該鋼材検査証明書の作成日から少なくとも90日経過後の0.2%耐力の向上代が40MPa以上であるレール。
V :0.30%以下、
Cu:1.0%以下、
Ni:1.0%以下、
Nb:0.05%以下、
Mo:0.5%以下、
Al:0.07%以下、
W :1.0%以下、
B :0.005%以下および
Ti:0.05%以下
からなる群より選択される1種または2種以上を含有する前記1に記載のレール。
C :0.70~0.85%、
Si:0.1~1.5%、
Mn:0.4~1.5%、
P :0.035%以下、
S :0.010%以下および
Cr:0.05~1.50%
を含有し、残部がFeおよび不可避的不純物の成分組成を有する鋼素材に熱間圧延を施してレールを作製し、該レールを100tf以上の荷重にて矯正した後、480時間以内に、少なくともレール頭部の0.2%耐力の測定結果を含む鋼材検査証明書を作成するレールの製造方法。
V :0.30%以下、
Cu:1.0%以下、
Ni:1.0%以下、
Nb:0.05%以下、
Mo:0.5%以下、
Al:0.07%以下、
W :1.0%以下、
B :0.005%以下および
Ti:0.05%以下
からなる群より選択される1種または2種以上を含有する前記3に記載のレールの製造方法。
本発明のレールについて具体的に説明する。本発明においては、レールが上記成分組成を有することが重要である。そこで、まず本発明において成分組成を上記のように限定する理由を説明する。なお、各成分の含有量の単位は「質量%」であるが、「%」と略記される。
Cは、パーライト組織においてセメンタイトを形成し、常温時効により0.2%耐力を向上させる効果を有する元素である。したがって、レールの0.2%耐力を確保するためにCの添加は必須であり、C含有量の増加に伴い0.2%耐力が向上する。すなわち、C含有量が0.70%未満であると、前記常温時効後に優れた0.2%耐力を得ることが難しい。一方、C含有量が0.85%を超えると、旧オーステナイト粒界に初析セメンタイトが生成し、却ってレールの耐疲労損傷性が低下する。したがって、C含有量は0.70~0.85%とする。好ましくは、0.75~0.85%である。
Siは、脱酸剤としての効果を有する元素である。また、Siは、パーライト中のフェライトへの固溶強化により、レールの0.2%耐力を向上させる効果を有している。そのため、Si含有量を0.1%以上とする必要がある。一方、Si含有量が1.5%を超えると、Siが有する高い酸素との結合力のため、酸化物系介在物が多量に生成するため、耐疲労損傷性が低下する。したがって、Si含有量は0.1~1.5%とする。好ましくは、0.15~1.5%である。
Mnは、鋼の変態温度を低下させてラメラー間隔を小さくすることにより、レールの高強度化に寄与する元素である。しかし、Mn含有量が0.4%未満では十分な効果が得られない。一方、Mn含有量が1.5%を超えると、鋼のミクロ偏析によりマルテンサイト組織を生じ易くなり、その結果、耐疲労損傷性が低下する。したがって、Mn含有量は0.4~1.5%とする。好ましくは、0.4~1.4%である。
P含有量が0.035%を超えると、レールの延性が低下する。そのため、P含有量は0.035%以下とする。一方、P含有量の下限は特に限定されず0%であってもよいが、工業的には0%超である。なお、P含有量を過度に低下させることは、精錬コストの増加を招くため、経済性の観点からは、P含有量を0.001%以上とすることが好ましい。より好ましくは、0.025%以下である。
Sは、主にA系(硫化物系)介在物の形態で鋼中に存在する。S含有量が0.010%を超えると前記介在物の量が著しく増加するとともに、粗大な介在物が生成するため、耐疲労損傷性が低下する。なお、S含有量を0.0005%未満とするには、精錬コストの増加を招くため、経済性の観点からは、S含有量を0.0005%以上とすることが好ましい。より好ましくは、0.009%以下である。
Crは、パーライト中のセメンタイトへの固溶強化により、0.2%耐力を向上させる効果を有する元素である。この効果を得るために、Cr含有量を0.05%以上とする必要がある。一方、Cr含有量が1.50%を超えると、Crの固溶強化によりマルテンサイト組織が生成するため、却って耐疲労損傷性が低下する。したがって、Cr含有量は0.05~1.50%とする。好ましくは、0.10~1.50%である。
V :0.30%以下、
Cu:1.0%以下、
Ni:1.0%以下、
Nb:0.05%以下、
Mo:0.5%以下、
Al:0.07%以下、
W :1.0%以下、
B :0.005%以下および
Ti:0.05%以下
からなる群より選択される1種または2種以上を、必要に応じてさらに含有することができる。
Vは、圧延中および圧延後に炭窒化物として析出し、析出強化により0.2%耐力を向上させる効果を有する元素である。そのためには、0.001%以上で添加することが好ましい。一方、V含有量が0.30%を超えると、粗大な炭窒化物が多量に析出するため、耐疲労損傷性の低下を招く。したがって、Vを添加する場合は、V含有量を0.30%以下とすることが好ましい。
Cuは、Crと同様に、固溶強化により0.2%耐力を向上させる効果を有する元素である。そのためには、0.001%以上で添加することが好ましい。一方、Cu含有量が1.0%を超えるとCu割れが生じる。したがって、Cuを添加する場合は、Cu含有量を1.0%以下とすることが好ましい。
Niは、延性を劣化することなく0.2%耐力を向上させる効果を有する。そのためには、0.001%以上で添加することが好ましい。また、NiをCuと複合添加することによってCu割れを抑制できるため、Cuを添加する場合にはNiも添加することが望ましい。一方、Ni含有量が1.0%を超えると、焼入れ性が上昇してマルテンサイトが生成する結果、耐疲労損傷性が低下する。したがって、Niを添加する場合は、Ni含有量を1.0%以下とすることが好ましい。
Nbは、圧延中及び圧延後に炭窒化物として析出し、パーライト系レールの0.2%耐力を向上させる。そのためには、0.001%以上で添加することが好ましい。一方、Nb含有量が0.05%を超えると、粗大な炭窒化物が多量に析出するため、延性が低下する。したがって、Nbを添加する場合は、Nb含有量を0.05%以下とすることが好ましい。
Moは、圧延中及び圧延後に炭化物として析出し、析出強化により0.2%耐力を向上させる。そのためには、0.001%以上で添加することが好ましい。一方、Mo含有量が0.5%を超えるとマルテンサイトが生成し、その結果、耐疲労損傷性が低下する。したがって、Moを添加する場合、Mo含有量を0.5%以下とすることが好ましい。
Alは、脱酸剤として添加される元素である。そのためには、0.001%以上で添加することが好ましい。一方、Al含有量が0.07%を超えると、Alの有する高い酸素との結合力のため、酸化物系介在物が多量に生成し、その結果、耐疲労損傷性が低下する。したがって、Al含有量は0.07%以下とすることが好ましい。
Wは、圧延中及び圧延後に炭化物として析出し、析出強化により0.2%耐力を向上させる。そのためには、0.001%以上で添加することが好ましい。一方、W含有量が1.0%を超えるとマルテンサイトが生成し、その結果、耐疲労損傷性が低下する。したがって、Wを添加する場合は、W含有量を1.0%以下とすることが好ましい。
Bは、圧延中及び圧延後に窒化物として析出し、析出強化により0.2%耐力を向上させる。そのためには、0.0001%以上で添加することが好ましい。しかし、B含有量が0.005%を超えるとマルテンサイトが生成し、その結果、耐疲労損傷性が低下する。そのため、Bを添加する場合、B含有量を0.005%以下とすることが好ましい。
Tiは、圧延中及び圧延後に炭化物、窒化物あるいは炭窒化物として析出し、析出強化により0.2%耐力を向上させる。そのためには、0.001%以上で添加することが好ましい。一方、Ti含有量が0.05%を超えると粗大な炭化物、窒化物あるいは炭窒化物が生成し、その結果、耐疲労損傷性が低下する。そのため、Tiを添加する場合、Ti含有量を0.05%以下とすることが好ましい。
本発明においては、レールが上記成分組成を有することに加えて、少なくともレール頭部の0.2%耐力の測定結果が記載されたレールの鋼材検査証明書における、0.2%耐力に対して、該鋼材検査証明書の作成日から少なくとも90日経過後の0.2%耐力の向上代が40MPa以上であることが肝要である。
さて、鋼材検査証明書には、レールの最終の製造工程を経たレールについて、機械的特性等の試験が行われた結果が記載される。そして、レールの出荷に当たっては、当該レールについての鋼材検査証明書が添付されて、客先へと発送される。本発明のレールは、この鋼材検査証明書が添付されるものであり、鋼材検査証明書には少なくともレールの頭部の0.2%耐力の測定結果が記載されている。ここで、記載されている0.2%耐力の測定結果は、レールの頭部から採取されたサンプルについて引張試験を行って得た実測値である。そして、鋼材検査証明書の作成日から少なくとも90日経過後には、当該鋼材検査証明書に記載された0.2%耐力に対して40MPa以上の0.2%耐力の向上があるので、通常、レールの出荷からレールの敷設まで90日以上あることを考慮すると、鋼材検査証明書に記載された0.2%耐力から予想される耐疲労損傷性に対してより向上した耐疲労損傷性を有するものとなる。もし、鋼材検査証明書の作成日からレールの敷設までにかかった時間が90日未満であったとしても、レール寿命は通常90日よりも大幅に長いので、レールの使用途中で、疲労損傷がレールに発生しない間に、鋼材検査証明書の作成日から90日が経過して0.2%耐力が上昇し、耐疲労損傷性が向上する。
なお、0.2%耐力の向上代は、鋼材検査証明書の作成日から少なくとも90日経過後以降に測定すればよいものであり、90日経過時点で測定しなくてはならないものではない。つまり、0.2%耐力の向上代の測定は、鋼材検査証明書の作成日の90日後であっても、1年以上後であってもよい。
この40MPa以上の0.2%耐力の向上を、レールの寿命を予測値に対する安全代と判断してもよいし、鋼材検査証明書の記載された0.2%耐力に対してさらに40MPaを上乗せした値をもとに、レールの寿命を予測するようにすることもできる。
次に、本発明のレールを製造する方法について説明する。
本発明に従うレールは、定法に従って、熱間圧延、次いで冷却によりレールを作製し、その後100tf以上の荷重での矯正処理を行うことによって製造することができる。
まず、転炉または電気炉で鋼を溶製し、必要に応じて脱ガスなどの二次精錬を経て、鋼の成分組成を上記範囲に調整する。次いで、連続鋳造を行ってブルームなどの鋼素材とする。次に、前記鋼素材を、加熱炉で1200~1350℃に加熱した後、熱間圧延してレールとする。前記熱間圧延は圧延終了温度:850~1000℃で行い、熱間圧延後のレールを冷却速度:1~10℃/sで冷却することが好ましい。
得られたレールのそれぞれについて引張試験を実施して、0.2%耐力、引張強さおよび伸びを測定した。また、耐疲労損傷性の試験を行って各レールの耐疲労損傷性を測定した。表2には、これら試験結果も併せて示す。測定方法は、以下の通りとした。なお、引張試験は、矯正処理から鋼材検査証明書作成までの間に行うとともに、No.1以外については常温時効処理を施した後にも実施した。
得られた各レールの頭部について、図1に示す部位から引張試験片を採取した。すなわち、引張試験片は、AREMA Chapter4の2.1.3.4に記載の位置(図1参照)からASTM A370に記載の平行部が12.7mmの引張試験片を採取した。次いで、得られた引張試験片を用い、引張速度:1mm/min、評点間距離:50mmの条件で引張試験を行って、0.2%耐力、引張強さおよび伸びを測定した。測定された値は表2に示した通りである。
耐疲労損傷性は、西原式摩耗試験機を用いて実際のレールと車輪の接触条件をシミュレートして評価した。すなわち、接触面を曲率半径15mmの曲面とした直径30mm(外径30mm、内径16mm)の円筒型試験片を、常温時効処理後のレールの図2(a)に示すレール頭部の部位から採取した。該円筒型試験片を、図2(b)に示すように接触圧力:2.2GPa、すべり率:-20%、油潤滑条件で試験機に供し、試験片接触面に剥離が発生した時点を疲労損傷寿命とした。疲労損傷寿命の大小を比較する際の基準として、現用のC量0.81%のパーライト鋼レールを採用し、該レール(A1)よりも10%以上疲労損傷時間が長い場合に耐疲労損傷性が向上したと判定した。
Claims (4)
- 少なくともレール頭部の0.2%耐力の測定結果が記載された鋼材検査証明書を備えるレールであって、
質量%で、
C :0.70~0.85%、
Si:0.1~1.5%、
Mn:0.4~1.5%、
P :0.035%以下、
S :0.010%以下および
Cr:0.05~1.50%
を含有し、残部がFeおよび不可避的不純物の成分組成を有し、
前記鋼材検査証明書に記載された0.2%耐力に対して、該鋼材検査証明書の作成日から少なくとも90日経過後の0.2%耐力の向上代が40MPa以上であるレール。 - 前記成分組成が、さらに質量%で、
V :0.30%以下、
Cu:1.0%以下、
Ni:1.0%以下、
Nb:0.05%以下、
Mo:0.5%以下、
Al:0.07%以下、
W :1.0%以下、
B :0.005%以下および
Ti:0.05%以下からなる群より選択される1種または2種以上を含有する請求項1に記載のレール。 - 質量%で、
C :0.70~0.85%、
Si:0.1~1.5%、
Mn:0.4~1.5%、
P :0.035%以下、
S :0.010%以下および
Cr:0.05~1.50%
を含有し、残部がFeおよび不可避的不純物の成分組成を有する鋼素材に熱間圧延を施してレールを作製し、該レールを100tf以上の荷重にて矯正した後、480時間以内に、少なくともレール頭部の0.2%耐力の測定結果を含む鋼材検査証明書を作成するレールの製造方法。 - 前記成分組成が、さらに質量%で、
V :0.30%以下、
Cu:1.0%以下、
Ni:1.0%以下、
Nb:0.05%以下、
Mo:0.5%以下、
Al:0.07%以下、
W :1.0%以下、
B :0.005%以下および
Ti:0.05%以下からなる群より選択される1種または2種以上を含有する請求項3に記載のレールの製造方法。
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BR112019017967-4A BR112019017967B1 (pt) | 2017-03-21 | 2018-03-20 | Trilho de alta resistência e método para produzir o mesmo |
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